Biodiversity loss

[27][28][29] The fast-growing extinction trends of various animal groups like mammals, birds, reptiles, amphibians, and fish have led scientists to declare a current biodiversity crisis in both land and ocean ecosystems.

[42][43] To measure biodiversity loss rates for a particular location, scientists record the species richness and its variation over time in that area.

[47] An October 2020 analysis by Swiss Re found that one-fifth of all countries are at risk of ecosystem collapse as the result of anthropogenic habitat destruction and increased wildlife loss.

They include habitat destruction, such as intensive agriculture, the use of pesticides (particularly insecticides), introduced species, and – to a lesser degree and only for some regions – the effects of climate change.

[72] Earthworms play an important role in ecosystem function,[72] helping with biological processing in soil, water, and even greenhouse gas balancing.

The possible causes include habitat destruction and modification, diseases, exploitation, pollution, pesticide use, introduced species, and ultraviolet-B radiation (UV-B).

Alongside the simultaneous halving of plant biomass, these striking declines are considered part of the prehistoric phase of the Holocene extinction.

[95] The majority are threatened by habitat loss, but activities such as logging of wild timber trees and collection of medicinal plants, or the introduction of non-native invasive species, also play a role.

[102][108] Examples of extinct marine species include Steller's sea cow (Hydrodamalis gigas) and the Caribbean monk seal (Monachus tropicalis).

For example, in the 1930s, the eelgrass limpet (Lottia alveus) became extinct in the Atlantic once the Zostera marina seagrass population declined upon exposure to a disease.

[102] The main causes of current biodiversity loss are: Jared Diamond describes an "Evil Quartet" of habitat destruction, overkill, introduced species and secondary extinctions.

[110] Edward O. Wilson suggested the acronym HIPPO for the main causes of biodiversity loss: Habitat destruction, Invasive species, Pollution, human over-Population and Over-harvesting.

[130] For example, "air pollution causes or contributes to acidification of lakes, eutrophication of estuaries and coastal waters, and mercury bioaccumulation in aquatic food webs".

[130] Noise generated by traffic, ships, vehicles, and aircraft can affect the survivability of wildlife species and can reach undisturbed habitats.

[132] One study found that as seismic noises and naval sonar increases in marine ecosystems, cetacean diversity decreases (including whales and dolphins).

[133] Multiple studies have found that fewer fishes, such as cod, haddock, rockfish, herring, sand seal, and blue whiting, have been spotted in areas with seismic noises, with catch rates declining by 40–80%.

[138] Fossil fuel extraction and associated oil and gas pipelines have major impacts on the biodiversity of many biomes due to land conversion, habitat loss and degradation, and pollution.

The term applies to natural resources such as water aquifers, grazing pastures and forests, wild medicinal plants, fish stocks and other wildlife.

A 2019 Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services report found that overfishing is the main driver of mass species extinction in oceans.

[149][150][1][11] Review articles, including the 2019 IPBES report, have also noted that human population growth and overconsumption are significant drivers of species decline.

[13] They argue that the main driver is the loss of habitat, caused by "the growth of commodities for export, particularly soybean and oil-palm, primarily for livestock feed or biofuel consumption in higher income economies.

[18][19] A 2021 collaborative report by scientists from the IPBES and the IPCC found that biodiversity loss and climate change must be addressed simultaneously, as they are inextricably linked and have similar effects on human well-being.

Due to this rapid change, for example cold-blooded animals (a category which includes amphibians, reptiles and all invertebrates) may struggle to find a suitable habitat within 50 km of their current location at the end of this century (for a mid-range scenario of future global warming).

"[185][186] The report also said, "Many of the drivers that have negative impacts on BFA (biodiversity for food and agriculture), including overexploitation, overharvesting, pollution, overuse of external inputs, and changes in land and water management, are at least partially caused by inappropriate agricultural practices"[187]: 6  and "transition to intensive production of a reduced number of species, breeds and varieties, remain major drivers of loss of BFA and ecosystem services.

[23][24] The 2020 CBD report highlighted that if the status quo does not change, biodiversity will continue to decline due to "currently unsustainable patterns of production and consumption, population growth and technological developments".

[199][200] The report also singled out Australia, Brazil, Cameroon and the Galapagos Islands (Ecuador) for having had one of its animals lost to extinction in the previous ten years.

[202] Some experts contend that the United States' refusal to ratify the Convention on Biological Diversity is harming global efforts to halt the extinction crisis.

[150][1] Others have raised concerns that the Convention on Biological Diversity does not go far enough, and argue the goal should be zero extinctions by 2050, along with cutting the impact of unsustainable food production on nature by half.

Its fifth target is: "Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity and, by 2020, protect and prevent the extinction of threatened species.

[210] Nearly three-quarters of bird species, two thirds of mammals and more than half of hard corals have been recorded at World Heritage Sites, even though they cover less than 1% of the planet.

Summary of major environmental-change categories that cause biodiversity loss. The data is expressed as a percentage of human-driven change (in red) relative to baseline (blue), as of 2021. Red indicates the percentage of the category that is damaged, lost, or otherwise affected, whereas blue indicates the percentage that is intact, remaining, or otherwise unaffected. [ 1 ]
Red list categories of the IUCN
Demonstrator against biodiversity loss, at Extinction Rebellion (2018).
The World Wildlife Fund's Living Planet Report 2022 found that wildlife populations declined by an average 69% since 1970. [ 48 ] [ 49 ] [ 50 ]
An annual decline of 5.2% in flying insect biomass found in nature reserves in Germany – about 75% loss in 26 years [ 55 ]
image of Earthworm on plant
Earthworm on plant
The golden toad of Monteverde , Costa Rica, was among the first casualties of amphibian declines. Formerly abundant, it was last seen in 1989.
Viola calcarata , a species highly vulnerable to climate change. [ 94 ]
Earth's 25 terrestrial hot spots of biodiversity . These regions contain a high number of plant and animal species and have been subjected to high levels of habitat destruction by human activity, leading to biodiversity loss.
Deforestation and increased road-building in the Amazon Rainforest in Bolivia cause significant concern because of increased human encroachment upon wild areas, increased resource extraction and further threats to biodiversity.
Industrial processes contributing to air pollution through the emission of carbon dioxide, sulfur dioxide, and nitrous oxide.
Potential for biodiversity loss from future fossil fuel extraction: Proportions of oil and gas field area overlapping with Protected Areas (PAs) (gray polygons) of different IUCN Protected Area management categories by UN regions: North America (a), Europe (b), West Asia (c), LAC (d), Africa (e), and Asia Pacific (f). Absolute area of overlap across all IUCN management categories is shown above histograms. Location of fields overlapping with PAs are shown in (g). Shading is used so that points can be visualized even where their spatial locations coincide, so darker points indicate higher densities of fields overlapping PAs. [ 139 ]
Mass fishing of Pacific jack mackerel (with possible bycatch) with a Chilean purse seiner .
Atlantic cod stocks were severely overexploited in the 1970s and 1980s, leading to their abrupt collapse in 1992 . [ 141 ]
The changing distribution of the world's land mammals in tonnes of carbon. The biomass of wild land mammals has declined by 85% since the emergence of humans. [ 147 ]
The relationship between the magnitude of climate variability and change (including both large increases and decreases in global temperature) and the extinction rate, over the past 450 million years. [ 158 ] This graph does not include the recent human made climate change .
Relative to now, key areas for wildlife will retain less of their biodiversity under 2 °C (3.6 °F) of global warming, and even less under 4.5 °C (8.1 °F). [ 173 ]
An infographic describing the relationship between biodiversity and food.
Red List Index (2019): The Red List Index (RLI) defines the conservation status of major species groups, and measures trends in the proportion of species expected to remain extant in the near future without additional conservation action. An RLI value of 1.0 equates to all species being categorised as 'Least Concern', and hence that none are expected to go extinct in the near future. A value of 0 indicates that all species have gone extinct. [ 193 ]